Classifying mill



March 16, 1965 Filed June 5, 1962 H. A. MERGES ETAL 3,

CLASSIFYING MILL 5 Sheets-Sheet 1 March 16, 1965 H. A. MERGES ETAL 7 CLASSIFYING MILL Filed June 5, 1962 5 Sheets-Sheet 2 March 1965 H. A. MERGES ETAL 3,

CLASSIFYINGMILL Filed June 5, 1962 5 Sheets-Sheet 5 March 16, 1965 H. A. MERGES ETAL 3,173,618

CLASSIFYING MILL Filed June 5, 1962 5 Sheets-Sheet 4 Fig. 6

March 16, 1965 H. A. MERGES ETAL 3,173,613

CLASSIFYING MILL Filed June 5, 1962 5 Sheets-Sheet 5 Fly. 7

United States Patent Claims. ot. 241-45 The present invention relates to a classifier, and, more particularly, to a mill-type classifier for grinding, classifying, and/or sifting both homogeneous materials such as paint or the like, and inhomogeneous matter as cereals, to any desired degree of fineness, irrespective of the presence of ingredients difiicult to pulverize, such as grain husks, Without changing constructional components of the mill, and without the need of regrinding the ground material.

Multi-purpose mills for several operations as grinding and classifying are well known in the art, but are applicable only to limited ranges of materials. Thus, conventional mills may be used either for grinding cereals alone or pigments alone, but not for both. Moreover, these mills in most cases depend on the presence of exhaustors and devices for the intake of secondary air required to control the classifying process. Thus, when the material is drawn through the exhaustor fans, the fine flour tends to settle on the blades of the fan where it forms undesirable flakes and bulky matter reappearing in the end product. Finally, conventional mills offer no possibility of processing and classifying certain materials in one operation. Some conventional machines are known to have a ring-shaped plate at the output end of the grinding elements, and the material ground is forced through the central aperture of the plate, however, without passing through a direct, spaceous classifying chamber in which a carefully designed, relatively undisturbed classifying flow would prevail.

It is accordingly a primary object of the present invention to provide a mill with the widest possible range of application.

It is another object of this invention to provide a multipurpose mill in which all grinding, classifying, and sifting operations are performed at the same time.

Another object of this invention is to provide, within the said mill, a uniform air flow of accurate dimensions for both homogeneous and inhomogeneous materials.

A further object of the invention is to achieve the results described above without any secondary air or additional exhaustors.

Finally, it is an object of the invention to provide a mill wherein the materials obtained as end products are either ground to the highest degree of fineness or ground coarser and sifted, or both.

These general features characteristic of the present invention may be complemented by special features provided for the purpose of achieving the objects set forth hereinbefore.

Basically, the mill in accordance with the present invention comprises a tapered grinding ring, whose diverging end faces the feed hopper, the grinding ring being so arranged as to axially cover the classifying chamber. A rotating disk provided centrally within the grinding ring has, at its circumference, regularly spaced heaters or grinding elements shaped to match the inner contours of the grinding ring.

According to a specific features of the arrangement, the heaters or grinding elements extend toward the converging end of the grinding ring, thereby defining by their inner edges the circumference of the classifying chamber.

According to another feature of this invention, the

Patented Mar. 16, 1965 heaters and the disk assembly are so dimensioned as to provide, between the outer edges of the beaters and the inner contours of the grinding ring, a distance much less than the distance between the said outer edges of the heaters and the disk circumference.

Another feature believed to be characteristic of the present invention is an annular channel, whose open side may be adjustably covered by a. plate. This annular channel is disposed adjacent the diverging end of the grinding ring and opens into an annular chamber.

Other features favorably bearing upon the grinding, classifying, and sifting processes will become apparent from the following detailed description of embodiments of the present invention with reference to the appended drawings wherein FIG. 1 is a section through the grinding, classifying, and sitting device according to an embodiment of the invention;

FIG. 2 is a plan view of the rotor disk used in the invention, complete with grinding elements;

FIG. 3 is a partial sectional view of the device in FIG. 1;

FIG. 4 is a schematic View of the flow conditions prevailing in the vicinity of a stationary grid mounted in front of a ring screen regulating the outlet aperture;

FIG. 5 is a section through another embodiment of the invention, in which the axially displaceable rotor disk is equipped with pins facing the feed hopper;

FIG. 6 is a section through still another embodiment of the invention where the cover has been replaced by a sifting bin, and

FIG. 7 is a sectional view of another embodiment according to the invention where an independently rotatable shown at 1, a housing with a cover 2 carrying a feed hop per 3. Housing 1 encloses a rotatably mounted rotor disk 4. The inner faces of housing 1 are designed as a tapered grinding ring 6, and rotor disk 4 with its grinding elements 5 rotates within grinding ring 6. This ring is arranged in such a manner that its diverging end faces feed hopper 3. An exchangeable or adjustable-aperture ring plate 7 is provided adjacent the converging end of grinding ring 6, thereby defining, together with rotor disk 4 and inner edges 8 of grinding elements 5, a classifying chamber 9. Cover 2 has an annular space or channel 10 that can be closed by an axially adjustable ring plate 11. When plate 11 is axially shifted, it may either contact an overflow plate 12 or, depending upon the arrangement of plate 12, engage the conical circumference 28 in cover 2. Disk 4 subdivides the inside of housing 1 into the said classifying chamber 9 and an input chamber 13. As shown in FIGS. 1 and 2, grinding elements 5 are disposed on rotor disk 4 at the outer circumference thereof, the grinding elements being preferably arranged in such a manner as to form a slight angle with the sense of rotation of rotor 4 as denoted by the arrow in FIG. 2. Grinding elements 5 are so dimensioned as to allow for axial displacement of rotor disk 4 between ring plates 7 and 12, with the effect of varying the distance between grinding elements 5 and tapered grinding ring 6, and, to a less degree, the width of classifying chamber 9.

Rotor disk 4 has such a diameter as to provide a passage from input chamber 13 to classifying chamber 9, and, thence, to a discharge channel 14. The outer ends 15' of rotor disk 4 are preferably slightly bent toward the diverging end of grinding ring 6, as shown in FIGS. 1 and 3. Alternatively, a cover plate (not shown) bent in a similar way may be secured to rotor disk 4. As shown in FIG. 2, the outer contours of rotor disk 4 may be provided with recesses 16. Furthermore, a ring grid 17 shown in FIGS. land 2 may be provided in a fixed rcla- 1 tion with respect .to rotor disk 4 opposite ring plate 7.

In an embodiment of the type described hereinbefore, the matcrial to be ground is fed from feed hopper 3 through inputv chamber 13 to a grinding zone 13;and, thence, to classifying chamber 9, aperture 19 of ring plate 7, and, finally, to dischargechannel 14. Plate ring 7 may ormay not be equipped with the van-type grid 17.

for its object the obtainingof it uniformly ground end product, the mill may be equipped at its input side with a ring plate that may be adjusted or closed, which enables structurally different ingredients of inhomogen'ous matter that are diliicult to disintegrate to be separated without impairing the fine-grinding of for instance the endosperm of grains ,or the like. By the mounting of such an adjust- Preferably, griding elements 5 are provided with ex- While the material flows from thediverging end of' grinding ring 6 to the converging end, it. is opposed by the force components resulting from the conical configuration of grinding ring 6- and heater elements 5. Owing to these force components the material tends to accumulate in region 21. This. is true of at least all the coarse particles of the material; hence, the effect is that of coarsely classifying the particles along the entire extension of grinding ring 6 in axial direction. Depending on whether ring plate 11 is open or closed, the coarse particles may then be discharged in sifted state .via annular channel 10,- as would .for instance be desirable in the case of cereals or simliar inhomogenous materials where husks and shells of kernels are separated in order. to be used as fodder, etc. If this is not desired, the

' able ring platethe range-of application of the mill is considerably increased. V

In'FIG. 5, an embodiment of the invention is shown which is similar to that in FIG. 1, except that rotor disk 4 is additionally equippedwith pins 23.. Also shown in coarse particles may remain in the grinding zone, untilcrushed or disintegrated to a degree of fineness permitting their conveyance by the air-flow existing during the grindin operation. I I p Upon leaving the grinding zone, the particles enter the relatively spacious classfying chamber 9 defined by ring plate 7,, rotor disk-4, and.inner edges 8 of grinding elements 5 The particles carried by the spiral-shaped airnew t i'avlto aperture 19 ,ofring plate 7, without being disturbed by any beaters or grinding elements provided at the input side of aperture 19 and rotating in the same or opposite sense .asrotor disk 4. Since the heaters 5 ,pro-' ject from the plane ofrotor disk 4 toward the outlet side of the mill, any coarser particles separated out in classifying chamber 9 and accumulating there are forcedby the circular or spiral air-flow into the effective range of grinding elements 5 and back into the grinding zone where they. are further pulverized.

As shown in FIGS. 2 and 4, grid 17 is rigidly secured to ring plate 7, the vanes of the grid being arranged in the sense of direction of the air-flow- This grid serves to additionally maintain the direction of. the air-flow and, as grinding marks on ring plate 7 have shown in tests, causes shifting eddy. currents vto be generated, thereby furthering theoverall classification:

' To insure that the particles to be ground are ied substantially through the entire grinding zone, the outer ends of rotor disk. 4 may be slightly bent toward the diverging end of. grinding ring 6,'thus causing the particles 7 upon hitting upon the face of disk 4 to travel more or less, toward the. diverging end of grinding ring 6. According. to a preferred embodiment, however, the outer ends of disk 4 are not bent, but instead a sheet-metal plate .is

secured thereto, whose outerportions are vslightly bent toward the diverging end of grinding ring 6, and this plate will then have the same effect. Naturally the arrangementof rotor disk 4 with respect to its hub will affect the position of the disk inside the mill housing, and thus will also elfcct the-size of chambers 9 and 13 so as to obtain the most favorable operating conditions In such a case'the grinding elements will project from the disk plane more or less to the diverging or converging endsof grinding ring 6, depending upon the position of the disk on its hub;

1 1; addition to thefeatures described above which have thisfigure are the conventional means foraxial displace merit of the disk. In this embodiment the simplified grinding elements need not extend toward the input. vside,

whereas they must project from the disk plane towards the output side, as described hereinbefore.

Moreover, an additional, preferably exchangeable flange 27 may be mounted on the outer circumference of .the

disk, to permit the free annular grinding slot between the. circumference of the disk and gricling ring- 6 to be -varied.'

It should be noted that intlie embodiments shown in FIGS. 1 and 5 further eddy. currents are generated at the input side ofthe mill between theirotor disk and the cover. In the upper section of themill these currents circulate clockwise, whereby the patricles are drawn away from the grinding zone toward the eddy currents and are then recirculated to thegrinding zone at higher speed because of the action of the grinding elements. This effect is further increased 'by the arrangement of pins 23 on rotor disk 4, for which purpose input chamber 13 is relatively roomy. In FIG. 6 another embodiment of theinvention is shown,

wherein annular channel 10 (FIG. 1) that may be opened or closed by the axially displaceable, plate 11 is connected with one of a number of possible Idischaring. devices as extension24; Preferably, this extension is at the lowest point ,providedwith a steeper discharge chute -or with a screw discharger. r p

According to the same embodiment, the facesof the grinding ring may-be either smooth or be provided with axially extending grooves of difierent' cross-sections. Alternatively, the grooves in the grinding ring may either gradually become less deep toward the converging end of shown wherein an independently rotatable vane-type,

wheel is, arranged adjacent'the. output side of the rotor disk, the speed of which wheel may for instance be .variable independently of the rotor-disk speed from O r.p.m.

to a value that permits the desired classification to be accomplished.

As is shown in FIG. 7, a wheel 30 having blades 31 is rotatably mounted inside classifying chamber 9 which is defined by output face 29 vof rotor disk 4,-inner edges 8 of beating, elements 5, and plate 7. Wheel 30, is secured -to a hollow shaft 32 whose one end projecting into the inside of the mill is streamlined;

The grinding stock is fed into feed hopper 3 and, thence, to the center of rotor'di'sk'4; A certain amount of'fine stock is then directly passed to sifter 30,31, without being ground in the grindingzone, because of the distance 33 between rotor disk 4 and grinding ring 6, or

because of recesses, if any.

When the degree of fineness of the particles matches the rotational speed of sitter 30, 31, the particles will pass the Sifter and flow into discharge chute 14. Conversely, when'the particles are still too coarse, after having been ground in the grinding zone, siften' 30, 31 rotating inde pendently of rotor disk '4- willbause these particles, in accordance with its'rotational speed, to be fed back to the grinding zone where they are further pulverized, until they are sufiiciently fine to pass the sifter.

It will be appreciated that the sifting wheel of the present invention is particularly easily accessible and exchangeable, thus permitting sifting wheels of conventional type with different numbers of vanes and different shapes, such as forwardly or backwardly bent vanes or radial vanes, to be easily mounted. If required, the mill may of course also be operated without operation of the sifting wheel.

While the novel features of the invention as applied to several preferred embodiments have been shown and de scribed, it will be obvious that modifications of the device illustrated may be made without departing from the spirit and the scope of the invention. Accordingly, the scope of this invention is to be governed by the language of the following claims construed in the light of the foregoing description of this invention.

What is claimed as new and desired to be secured by Letters Patent is:

1. A device for disintegrating, sifting and separating material comprising, a housing having a central inlet, a tapered grinding ring mounted within said housing having its diverging end facing the housing inlet, a rotor disk axially arranged within said grinding ring and having beating means shaped to match the contour of said grinding ring mounted thereon, said beating means projecting from the periphery of said rotor disk toward the converging end of said grinding ring, the outer edges of said beating means and the inner contour of said grinding ring defining an annular grinding zone, the height of which being substantially less than the distance between the outer edges of said beating means and the circumference of said rotor disk, a first annular plate mounted at the converging edge of said grinding ring, said first annular plate, said rotor disk and the inner projecting edges of said beating means defining a classifying chamber, said housing being provided with an annular chamber disposed in front of the diverging end of said grinding ring and a second annular plate forming a slot therewith for entry into said forward chamber.

2. The device according to claim 1 wherein the peripheral edges of the rotor disk member are bent toward the inlet side of the device.

3. The device according to claim 1 wherein the rotor disk member is axially displaceable within the extension of width of the grinding ring member.

4. The device according to claim 1 wherein at the input side the grinding face of the grinding ring member is provided with grooves, or the like, over half the width of the ring, while the other half of width of said grinding ring is designed as a smooth, tapered ring area.

5. The device according to claim 1 wherein a preferably exchangeable flange member is mounted on the circumference of the rotor disk member.

6. The device according to claim 1 wherein a sifting wheel is mounted within the classifying chamber, said sifting wheel being provided with vanes, or the like, and being rotatable independently of the rotor disk member.

7. The device according to claim 1 wherein a hollow shaft member is provided for carrying the sifting wheel, the end portion of said hollow shaft member extending into the housing of the mill being semicircularly streamlined so as to obtain favorable flow conditions.

8. The device according to claim 1 wherein the forward annular chamber is disposed in a cover for said housing and wherein said second annular plate, forming said slot, in adjustable and said slot is variable in size.

9. The device according to claim 8 wherein said forward annular chamber is formed by a housing arranged on the cover, the peripheral wall of said housing being tapered in accordance with the tapered grinding ring.

10. The device according to claim 1 including a grid member mounted on the first mentioned annular plate.

References (Cited by the Examiner UNITED STATES PATENTS 258,194 5/82 Cook 24149 795,133 7/05 Johnson 24156 1,260,406 3/18 Lachmann et a1 241--56 1,861,779 6/32 Bornhauser 241 2,361,278 10/44 Evans 24156 2,522,027 9/50 Evans 24156 2,573,129 10/51 Dulait 241-55 2,774,543 12/56 Keller et al. 24155 2,939,638 6/60 Haigh et a1. 24155 FOREIGN PATENTS 558,893 7/57 Belgium. 286,202 2/53 Switzerland.

I. SPENCER OVERHOLSER, Primary Examiner. 

1. A DEVICE FOR DISINTEGRATING, SIFTING AND SEPARATING MATERIAL COMPRISING, A HOUSING HAVING A CENTRAL INLET, A TAPERED GRINDING RING MOUNTED WITHIN SAID HAVING ITS DIVERGING END FACING THE HOUSING INLET, A ROTOR DISK AXIALLY ARRANGED WITHIN SAID GRINDING RING AND HAVING BEATING MEANS SHAPED TO MATCH THE CONTOUR OF SAID GRINDING RING MOUNTED THEREON, SAID BEATING MEANS PROJECTING FROM THE PERIPHERY OF SAID ROTOR DISK TOWARD THE CONVERGING END OF SAID GRINDING RING, THE OUTER EDGED OF SAID BEATING MEANS AND THE INNER CONTOUR OF SAID GRINDING RING DEFINING AN ANNULAR GRINDING ZONE, THE HEIGHT OF WHICH 